Field of the Invention
Numerous deposit forming substances are inherent in hydrocarbon fuels. These substances when used in internal combustion engines tend to form deposits on and around constricted areas of the engine contacted by the fuel. Typical areas commonly and sometimes seriously burdened by the formation of deposits include carburetor ports, throttle body and venturies, engine intake valves, etc.
Deposits adversely affect the operation of the vehicle. For example, deposits on the carburetor throttle body and venturies increase the fuel to air ratio of the gas mixture to the combustion chamber thereby increasing the amount of unburned hydrocarbon and carbon monoxide discharged from the chamber. The high fuel-air ratio also reduces the gas mileage obtainable from the vehicle.
Deposits on the engine intake valves when they get sufficiently heavy, on the other hand, restrict the gas mixture flow into the combustion chamber. This restriction, starves the engine of air and fuel and results in a loss of power. Deposits on the valves also increase the probability of valve failure due to burning and improper valve seating. In addition, these deposits may break off and enter the combustion chamber possibly resulting in mechanical damage to the piston, piston rings, engine head, etc.
The formation of these deposits can be inhibited as well as removed by incorporating an active detergent into the fuel. Numerous fuel detergents are currently available and many are commercially employed in national brand fuels. While these detergents function to varying degrees in cleaning carburetor throttle bodies and venturies or in maintaining intake valves with reduced deposits, or in cleaning other areas such as the PCV valve, etc., only a few detergents are available to clean and maintain all of the contacted areas effectively clean. Those detergents having this property are referred to hereinafter as a broad range detergent. Those few broad range detergents available must be employed at relatively high concentrations in order to maintain their effectiveness. The employment of these high concentrations has the burdens of high costs and reduces the water tolerance properties of the fuel.
In addition to having the broad range detergent properties, it is an additional advantage of the fuel detergent to have dispersant properties. In the operation of an internal combustion engine, a small amount of the fuel additives inevitably finds access to the crankcase and admixes with the crankcase oil. The continued presence of small amounts of dispersants within the crankcase oil increase the ability of the oil to maintain sludges and the like dispersed. Thus, by developing an additive having both broad range detergency and dispersancy, those parts of the engine contacted by the fuel can be maintained effectively clean and, at the same time, those parts of the engine contacted by the crankcase oil can be maintained with reduced sludge and varnish deposits.
A class of fuel additives has recently been developed which exhibits excellent broad range detergency and good dispersancy. This class of fuel detergentdispersant additives is commonly known as the polybutene amines. Several patents disclosing the preparation and use of exemplary polybutene amines include U.S. Pat. Nos. 3,438,757; 3,565,804; 3,574,576 and 3,671,511. The polybutene amines disclosed in these patents exhibit remarkable broad range detergent-dispersant properties and their use has significantly increased the operating efficiency and has reduced the maintenance of vehicles operating on fuels containing the additive.
A problem appurtenant to the use of the polybutene amines is that of adverse economics. The additives are normally employed at a concentration between 250 and 400 parts per million for best results. Although these concentrations are relatively small, the use of the additives in gasoline fuels which are sold in vast quantities at low profits results in a substantial cost burden to the petroleum fuel suppliers. Thus, a reduction of the effective concentration of the additive to the order of 150 to 250 pers parts per million would result in a considerable economic savings.
It is therefore an object of this invention to provide a fuel additive having broad range detergent properties.
It is an additional object of this invention to provide a fuel additive having broad range detergent and dispersant properties.
It is another object of this invention to provide a fuel additive having broad range detergent properties which may be effectively employed at low concentrations.
It is another object of this invention to provide a fuel additive having broad range detergency which may be employed in fuels at low concentrations without sacrificing a loss in detergency obtained from conventional detergents.
Other objects of this invention will become apparent from the following description of the invention nd appended claims.